The invention relates to a paving stone, in particular made of concrete or the like, according to the precharacterizing clause of claim 1.
In the case of many known paving stone surfacings that are interlocked against lateral displacement, over time the stones are loosened in the linkage. Braking forces of vehicles driving on the surfacing cause the stones to be displaced in the direction of travel. Sand in the joints thereby flows away into the substructure or into the bed of chippings lying thereunder. This makes the stones free by the amount of play provided by the sand filling and they can easily shift both in the horizontal direction and in the vertical direction within a certain latitude. When driving on such a surfacing, this is noticeable from corresponding rolling noises.
To obtain a more stable paving stone linkage, in the past vertical interlocking formations have already been provided on paving stones. Such interlocking formations are to be found for example in EP 752 500 or in the document cited therein DE 70 28 919. Both prior-art configurations are provided on at least one side both with lugs and with niches. Although reliable vertical interlocking is achieved as a result, the laying of such paving stones is made difficult, since these paving stones are to be joined one onto the other only in a horizontal laying direction. This hinders laying by machine with corresponding lifting equipment and always entails the risk that, if there is a horizontal offset of the paving stones, material from the substructure is pushed together and gets between the sides of the stones.
It is therefore an object of the invention to propose a paving stone which has the advantages of vertical interlocking but can be laid in the vertical direction in a customary way.
This object is achieved on the basis of a paving stone of the type stated at the beginning by the characterizing features of claim 1.
Advantageous configurations and developments of the invention are possible by the measures stated in the subclaims.
Accordingly, a paving stone according to the invention is distinguished by the fact that only overengaging or only underengaging interlocking elements are respectively provided on each side of the paving stone provided with vertical interlocking elements. This makes it possible to join a paving stone with a side having only overengaging interlocking elements from above onto a side of an adjacent stone which has only underengaging interlocking elements. After laying, the paving stone with the overengaging interlocking elements secures the adjacent paving stone with underengaging interlocking elements in the vertical direction.
A paving stone according to the invention may be designed for example in such a way that one side is provided with overengaging interlocking elements and the opposite side is provided with underengaging interlocking elements. Consequently, the paving stone linkage can be laid row by row by customary placement from above. The two remaining side walls may be designed without vertical interlocking and consequently in such a way that they are freely displaceable in the vertical direction with respect to adjacent stones. In this embodiment, the vertical interlocking takes place from one row of stones to the next row of stones.
In a particularly advantageous embodiment of the invention, on the other hand, two orthogonally adjoining adjacent sides of the stone are provided with overengaging interlocking elements and two orthogonally adjoining adjacent sides of the stone are provided with underengaging interlocking elements. Such stones can continue as before to be placed in the laying direction from above into the already laid part of the paving stone linkage. As before, the paving stone linkage can be laid row by row, the respectively newly laid row being built up from one side. The paving stone to be laid next is laid into the corner formed between two stones of adjacent rows of paving stones and secures both adjacent stones in the vertical direction.
In one particular embodiment of the invention, the upper and lower interlocking elements are designed as lateral lugs. This has production-engineering advantages over the known configurations with niches.
In an advantageous exemplary embodiment of the invention, two or more lugs are provided on one side of the stone. This results in a more effective interlocking of the individual stones.
In a preferred embodiment of the invention, pockets for joint material are provided in the laid stone linkage, said pockets being formed for example by the interlocking elements and the joints between individual interlocking elements formed by adjacent interlocking faces ending in the lower region of said pockets.
A certain amount of joint material can as it were be kept in reserve in said pockets. This joint material, which generally consists of fine sand, finds its way downward over time through the joints formed between the interlocking elements and settles in the substructure. The replenishment from said deposits or pockets ensures over quite a long period of time that there is always adequate joint material between the contact faces of individual stones. This is necessary for a stable paving stone linkage. On account of the reserve of joint material that can be taken up in the stone linkage, new material needs to be introduced from above only at comparatively great intervals in the case of a stone linkage according to the invention.
In a development of this embodiment, the interlocking elements are designed in such a way that the underengaging interlocking elements protrude laterally of the [sic] overengaging interlocking elements, but end in height below the overengaging interlocking elements. As a result, such a reserve pocket is formed between the individual interlocking elements.
It is also advantageous if, in this embodiment, the overengaging interlocking element is designed such that it falls away laterally on its upper side. This has the consequence that joint material brought to it from above can pass laterally into the pockets formed between the individual interlocking elements.
In one particular embodiment in this respect, the overengaging interlocking element is provided with a roof slope under a central gable. This roof shape offers a maximum angle of inclination over the entire width of the interlocking element, the central arrangement of the gable providing a smooth sliding path for the joint material on both sides of the gable.
In a particularly advantageous embodiment of the invention, the interlocking faces of adjacent interlocking elements are obliquely designed. In comparison with other, for example stepped shapes, this facilitates the replenishment of the downwardly disappearing joint material in the joints between the oblique interlocking faces, said joints likewise being of an oblique design.
The reserve pockets for the joint material are preferably formed at a certain distance from the upper edge of the pavement or sidewalk surfacing. When it is driven over, a certain vacuum or suction effect causes the material to be drawn away upward out of the stone linkage in the upper region between individual stones. Only when there is a certain distance of several centimeters from the upper edge of the paving stones it is ensured that the joint material kept in reserve remains in the reserve pockets.
Furthermore, it is advantageous if the underengaging interlocking elements of a particular paving stone have interlocking faces running perpendicularly downward. In this way, a stone which can be referred to as a so-called xe2x80x9ckey stonexe2x80x9d is obtained. This stone has the property that it can be removed from the paving stone linkage even when it is surrounded by paving stones on all sides. Consequently, key stones can be provided at specific locations of the paving stone surfacing, allowing the paving stone surfacing to be taken up without damaging a stone or taking up unnecessarily large areas. In this case, the xe2x80x9ckey stonexe2x80x9d may have a special marking, for example a half-groove or the like that is perceptible from above, in order to identify the stone in the laid area.
In a particularly advantageous embodiment of the invention, the overengaging interlocking elements are designed as xe2x80x9csetbacksxe2x80x9d, i.e. indentations in the side wall. This design allows a possibly desired laying of the stones without joints. However, here, too, a lateral spacer has the effect of laying with joints. Furthermore, the stone with two planar side faces can be laid particularly well by machine, since optimum contacting or gripping faces are available.